Nature of the active sites in haemocyanin and iron nickel hydrogenases: the bond valence sum approach

1995 ◽  
pp. 1177 ◽  
Author(s):  
Sanchita Hati ◽  
Dipankar Datta
Keyword(s):  
Active Sites ◽  
Bond Valence ◽  
Iron Nickel ◽  
Bond Valence Sum

3DBVSMAPPER: a program for automatically generating bond-valence sum landscapes

2012 ◽  
Vol 45 (5) ◽  
pp. 1054-1056 ◽  
Author(s):  
Matthew Sale ◽  
Maxim Avdeev
Keyword(s):  
Computer Program ◽  
Three Dimensional ◽  
Bond Valence ◽  
Spatial Distributions ◽  
Energy Landscapes ◽  
Bond Valence Sum ◽  
Scripting Language ◽  
Materials Studio ◽  
User Intervention ◽  
Minimal User Intervention

A computer program,3DBVSMAPPER, was developed to generate bond-valence sum maps and bond-valence energy landscapes with minimal user intervention. The program is designed to calculate the spatial distributions of bond-valence values on three-dimensional grids, and to identify infinitely connected isosurfaces in these spatial distributions for a given bond-valence mismatch or energy threshold and extract their volume and surface area characteristics. It is implemented in the Perl scripting language embedded in AccelrysMaterials Studioand has the capacity to process automatically an unlimited number of materials using crystallographic information files as input.

VALMAP2.0: contour maps using the bond-valence-sum method

1999 ◽  
Vol 32 (2) ◽  
pp. 341-344 ◽  
Author(s):  
Javier González-Platas ◽  
Cristina González-Silgo ◽  
Catalina Ruiz-Pérez
Keyword(s):  
Arbitrary Point ◽  
Bond Valence ◽  
Steric Effects ◽  
Contour Map ◽  
Structural Investigations ◽  
Disorder Phase Transition ◽  
Contour Maps ◽  
Bond Valence Sum ◽  
Bond Valence Model ◽  
Microsoft Windows

VALMAP2.0 is a Microsoft-Windows-based program designed to assist material scientists in accurate structural investigations. The aim ofVALMAPis to calculate the sum of bond valences that a particular atom would have if it were placed at any arbitrary point in the crystal. By movement of this atom through all possible points, its valence-sum contour map can be displayed. Parameters of the bond-valence model are available and may be modified. The program was tested in a number of cases and two examples of applications are reported: (i) finding probable atom sites in crystal structures; (ii) displacive and order–disorder phase transition mechanisms, analysing steric effects.

SUBSTITUTION EFFECT IN Pr-DOPED YBCO

2006 ◽  
Vol 20 (20) ◽  
pp. 2899-2907
Author(s):  
L. ZHANG ◽  
M. WANG ◽  
Y. Y. XU
Keyword(s):  
Rietveld Refinement ◽  
Reference System ◽  
Structural Changes ◽  
Substitution Effect ◽  
Bond Valence ◽  
X Ray Diffraction ◽  
Dc Magnetization ◽  
X Ray ◽  
Bond Lengths ◽  
Bond Valence Sum

A series of samples of Y 1-x Pr x Ba 2 Cu 3 O y ( YPrBCO ) with 0.05 ≤ x ≤ 0.6 was synthesized and characterized by DC magnetization, X-ray diffraction (XRD), and Rietveld refinement. It is found that besides Pr substitution for Y , a part of Pr substituted for Ba in YBa 2 Cu 3 O y (YBCO), and the amount of Pr in the Y and Ba positions, respectively, is estimated by the refinement with the help of bond valence sum (BVS) calculation. By comparing the correlation of structural changes such as Ba-O (4) and Cu (1, 2)- O (4) bond lengths and superconductivity between our system with the reference system where Pr just replaces Y , structural evidences are found to explain Pr substitution for Ba suppresses Tc more strongly than that for Y .

scholarly journals Double salt crystal structure of hexasodium hemiundecahydrogenα-hexamolybdoplatinate(IV) heminonahydrogenα-hexamolybdoplatinate(IV) nonacosahydrate: dihydrogen disordered-mixture double salt

2015 ◽  
Vol 71 (10) ◽  
pp. 1250-1254 ◽  
Author(s):  
Hea-Chung Joo ◽  
Ki-Min Park ◽  
Uk Lee
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Hydrothermal Reaction ◽  
Bond Distance ◽  
Bond Valence ◽  
Double Salt ◽  
Charge Balance ◽  
Salt Crystal ◽  
Bond Valence Sum ◽  
Difference Fourier

The title double salt containing two distinct, differently protonated hexamolybdoplatinate(IV) polyanions, Na6[H5.5α-PtMo6O24][H4.5α-PtMo6O24]·29H2O, has been synthesized by a hydrothermal reaction atcapH 1.80. The positions of the H atoms in the polyanions were established from difference Fourier maps and confirmed by the interpolyanion hydrogen bonds, bond-distance elongation, and bond-valence sum (BVS) calculations. The fractional numbers of H atoms in each polyanion are required for charge balance and in order to avoid unrealistically short H...H distances in the interpolyanion hydrogen bonds. Considering the disorder, the refined formula of the title polyanion, {[H5.5α-PtMo6O24]; polyanion (A) and [H4.5α-PtMo6O24]; polyanion (B)}6−, can be rewritten as a set of real formula,viz. {[H6α-PtMo6O24]; polyanion (A). [H4α-PtMo6O24]; polyanion (B)}6−and {[H5α-PtMo6O24]; polyanion (A). [H5α-PtMo6O24]; polyanion (B)}6−. The polyanion pairs both form dimers of the same formula,viz. {[H10α-Pt2Mo12O48]}6−connected by seven interpolyanion O—H...O hydrogen bonds.

New Bond-Valence Sum Model

1997 ◽  
Vol 53 (6) ◽  
pp. 885-894 ◽  
Author(s):  
J. P. Naskar ◽  
S. Hati ◽  
D. Datta
Keyword(s):  
Oxidation State ◽  
Coordination Sphere ◽  
Metal Ion ◽  
Nickel Complexes ◽  
Bond Valence ◽  
Oxidation States ◽  
Linear Variation ◽  
Axial Bond ◽  
Inorganic Complexes ◽  
Bond Valence Sum

A new expression is devised empirically to accommodate zero and some negative oxidation states in the bond-valence sum approach. The method is worked out in detail for a number of homoleptic copper and nickel complexes of various coordinating atoms in several oxidation states of the metals. An implication of the expression is a linear variation between 1/r eq and 1/r ax in octahedral MX 6 moieties, where r eq and r ax are, respectively, the average equatorial and axial bond lengths. This is verified in Cu2+ X 6 chromophores for X = F, O, N and S. The usefulness of the new expression in assessing the compatibility of a coordination sphere with an oxidation state of a metal ion is demonstrated by exemplary applications to some inorganic complexes, azurin and urease.

scholarly journals 3DBVSMAPPER: a program for automatically generating bond-valence sum landscapes. Corrigendum

2017 ◽  
Vol 50 (6) ◽  
pp. 1852-1852 ◽  
Author(s):  
Matthew Sale ◽  
Maxim Avdeev
Keyword(s):  
Bond Valence ◽  
Bond Valence Sum

An equation in the article by Sale & Avdeev [J. Appl. Cryst.(2012),45, 1054–1056] is corrected.

Sign in / Sign up

Export Citation Format

Share Document